In U.S. Pat. Application Ser. No. 166,748 filed Mar. 8, 1988, now U.S. Pat. No. 4,820,537, a method for decaffeinating coffee with a supercritical fluid is disclosed. This disclosed invention involves the continuous feeding of an essentially caffeine-free supercritical fluid to one end of an extraction vessel containing green coffee beans and continuously withdrawing a caffeine-laden supercritical fluid from the opposite end. A portion of the decaffeinated beans is periodically discharged while a fresh portion of undecaffeinated beans is essentially simultaneously charged to the extraction vessel. One suggested supercritical fluid is carbon dioxide.
In U.S. Pat. No. 2,555,052 (Morse), a chamber adapted for continuous flow of a granular substance therethrough is disclosed. The contacting vessel comprises an upper cylindrical section and a lower conical bottom having a hole at the apex of the cone for the discharge of the solid particles. A deflecting member comprising two regular and opposite cones having a common base is concentrically positioned in the chamber so that the common base lies in the plane formed by the intersection of the conical sides with the conical bottom.
In U.S. Pat. No. 4,060,394 (Orebe et al), a bottom closure for a chemical reactor is disclosed. This bottom closure is conically shaped and bears against a conical countersurface. The closure extends upwardly a sufficient distance into the center of the reactor to destroy solid bridges or arches during the opening of the closure.